lora: replace custom fri3d_2026 SX1262 driver with upstream micropython-lib driver + adapter - #231

…me to 5ms

Two fixes in the adapter (no upstream changes):

1. Clear device errors before configure() in begin(). After TCXO init
   in the upstream constructor, the datasheet-expected XOSC_START_ERR
   (0x20) can reappear between __init__ and the first configure()
   call on some boards. _check_error() at the end of configure()
   treats it as fatal → RuntimeError. Clearing stale errors first
   fixes this; any genuine errors from configure() itself are still
   caught by its own _check_error() call.

2. Bump dio3_tcxo_start_time_us from 1000→5000 to match the old
   driver's default TCXO delay, giving slow-starting oscillators
   more margin.

lora_adapter.py:
- Add sys.print_exception(e) in both blocking and non-blocking send()
  branches so the actual exception is visible on serial (was swallowed
  by bare except: return 0, -1)
- Same in _irq_handler for poll_send() exceptions

lora_manager.py:
- reset_chip(): wrap exp.config writes with
  mpos.ui.task_handler.disable()/enable() to avoid I2C bus contention
  between the config write and LVGL's periodic expander reads
  (buttons, joystick). Without this, config register writes silently
  fail on CH32 firmware v2.0.1 — see issue #224.
- Use try/finally to guarantee task_handler is re-enabled even if the
  write raises.

The upstream prepare_send() calls _standby() with STDBY_XOSC mode (1),
which turns on the crystal oscillator. Per DS 13.3.6, this sets
XOSC_START_ERR (0x20). On some boards the XOSC stabilizes fast enough
that the flag clears before _check_error() runs — on others (socketed
modules, different TCXO path) it doesn't, causing RuntimeError on
every send.

Fix: _clear_errors() before prepare_send() in both blocking and
non-blocking paths. Safe because prepare_send() has its own
_check_error() that catches genuinely new errors from the standby
and setup commands.

Per DS 13.3.6, XOSC_START_ERR (0x20) is expected after any transition
that restarts the crystal oscillator — notably _standby() with
STDBY_XOSC mode (1), called by prepare_send() and start_recv().
The upstream constructor clears it once after TCXO init, but the error
reappears after every subsequent STDBY_XOSC transition. On some
hardware (socketed modules, slower oscillators) the flag stays set
long enough for the immediately-following _check_error() to raise.

Fix: skip raising on op_error 0x20. All other errors still raise.
This is the second upstream deviation in sx126x.py (after the
machine.Pin try/except for Unix desktop compat).

…ble soft IRQ

MicroPython const() values in compiled .mpy modules are compile-time
inlined and not importable across modules. The previous attempt to
import _IRQ_TX_DONE etc. from lora.sx126x fails at boot with
'ImportError: cant import name _IRQ_TX_DONE'.

Define the hardware register masks locally with private names
(_TX_DONE, _RX_DONE, _CRC_ERR) and expose them as public class
attributes (PolledSX126x.TX_DONE etc.).

Use SPI.Device.lock()/unlock() (C-level spi_device_acquire_bus /
spi_device_release_bus) in write_readinto() and readinto() so the shared
SPI bus can't be preempted between per-byte calls while CS is held low.

Closes the remaining gap from PR #222.